CRT designation systems

Every Cathode-Ray Tube (henceforth CRT) has a label applied on the funnel bearing the tube type number along with other information (certifications, warnings, etc.). The type number is an alphanumeric sequence where (groups of) letters and numbers define various features of the tube (application, size, etc.). Prior to the introduction of a universal system, each region active in CRT manufacturing (USA, Europe, Japan) had its own system for CRT designations[1].

American System (EIA)

The type number consists of three symbols and optionally one or more suffixes.

Examples: 19VLUP22, 22VABP4B, 25VABP22A

The first symbol consists of a number followed by a V. The number is the average measure in inches of the diagonal of the viewable screen, i.e. the useful phosphor screen area where the picture is displayed. A value between -1/2 inch and +1/2 inch of a whole number is indicated with the whole number. A value exactly in the middle of two successive whole numbers is indicated with the immediately inferior whole number. According to the EIA system, since 1967 for TV sets and december 1969 for bare tubes, the dimensions no longer indicate the face diagonal but the viewable screen diagonal. This is made explicit by the letter V after the dimensions digits. For instance, a CRT previously designated as 25AP22A now becomes 23VAP22A.

The second symbol consists of one or more letters designating a specific CRT family whose members have common optical, electrical and mechanical characteristics.

The third symbol consists of the letter P followed by a number indicating the characteristics of the phosphor. For instance, P22 designates a colour picture tube phosphor and P4 a monochrome tube phosphor.

European System (Pro Electron)

The first symbol is a letter that defines the application category of the tube:

A

direct view tube for domestic TV

D

single trace oscilloscope tube

E

multiple trace oscilloscope tube

F

direct view radar tube

L

display storage tube

M

direct view tube for professional TV (monitor)

P

projection tube for professional use

Q

flying spot scanner

With a few exceptions, only A tubes are used for TV receivers and arcade monitors. The difference between A and M tubes concerns the spacing or pitch between corresponding points on line trios at screen center: this value is approximately 0.82mm for 110° A tubes and 0.66-to-0.82mm for 90° A tubes[2]. M tubes have a finer pitch as they are usually reserved for professional monitors where the user sits at a closer distance from the screen.

The second symbol is a two-digit number designating the minimum diagonal in centimeters of the CRT face (e.g. 51 = 51cm).

The third symbol is a three-digit number (for monochrome tubes two digits are also possible) separated from the second symbol by a hyphen. It designates a specific CRT family whose members have common optical, electrical and mechanical characteristics.

Japanese System (EIAJ)

According to this system (adopted also by other Asian manufacturers), the type number consists of three to four symbols.

Examples: 3708B22, 420FLB22, 470MTB22, 510UEB22-TC01

The first symbol is a three-digit number designating the minimum diagonal in millimeters of the CRT face (e.g. 370 = 370mm or 37cm).

The second symbol consists of one to two letters (or numbers) designating a specific CRT family whose members have common optical, electrical and mechanical characteristics.

The third symbol consists of the letter B followed by a number designating the phosphor type. For instance, B22 designates a color picture tube phosphor and is the EIAJ equivalent of P22 in the EIA system and X in the Pro Electron system. B4 designates a monochrome tube phosphor and is the EIAJ equivalent of P4 in the EIA system and W in the Pro Electron system.

The fourth symbol or suffix (e.g TC01, TC02, TC03, etc.), separated from the main type number by a hyphen, is only used for tubes having integral neck components (bonded yokes and adjustment rings).

Worldwide Type Designation System

On April 1st 1982 the three type assignment agencies EIA, Pro Electron and EIAJ jointly established a new universal system for CRT designations. The system covers color and monochrome TV picture tubes for consumer receiver applications and color and monochrome monitor or display tubes for direct view, raster scan applications other than consumer TV.

According to this system the type number consists of five to six symbols of alternating groups of letters and numbers.

Examples: A48EAX13X01, A59JMZ40X04, M68JUA068X, W76ERF342X044

The first symbol is a letter that defines the application category of the tube:

A

direct view tube for domestic TV

M

direct view tube for professional TV (monitor)

W

direct view widescreen tube for domestic TV

Note: Tubes in Sony widescreen (16:9) professional monitors can have "M" or "S" as the first symbol (e.g. M57LRX21X in BVM-D24E1W/E/A and S76LTD21X in BVM-D32E1WU/E/A).

For the difference between A and M tubes, see above under the European system (Pro Electron).
Note: some manufacturers (e.g. Sony, Panasonic) use M tubes not only for professional monitors but also for some of their consumer TV receivers.

The second symbol defines the minimum viewable screen diagonal (projected) and consists of a two-digit number. This number is determined by the glass panel design-centre value in centimeters of the minimum viewable screen diagonal. A tube having its screen size within plus or minus 1/2 centimeter is assigned that integer. A tube falling exactly on a one-half centimeter is assigned the next larger integer.

The third symbol designates the family code and consists of three letters excluding I and O (to avoid confusion with 1 and 0). It defines a specific CRT family whose members have common optical, electrical and mechanical characteristics. It is assigned in alphabetical sequence from left to right (AAA, AAB, AAC, ...AZZ, BAA, ...BZZ, ...ZZZ). Once a letter combination has been assigned to a sponsor for a particular tube type, that combination will be reserved for future assignments to the original sponsor. In this way the same combination will be available to a sponsor so that the familiy relationship may be maintained for different sizes. However, with permission of the original sponsor, other manufacturers may specify assignments in the same family.

The third symbol letters are allocated in blocks to the three type assignment agencies as follows:

EIA (USA)

AAA through DZZ

Pro Electron (Europe)

EAA through HZZ

EIA (Japan)

JAA through MZZ

Note: seeming counterexamples to this distribution can usually be explained by custom labelling: when using tubes of different makes in their own receivers, some TV manufacturers require from the tube manufacturer a label bearing their name and often omitting the tube manufacturer's name. As a result, a tube made in one region may end up with the label of a manufacturer from another region:

Philips-labelled Toshiba tube

Philips-labelled Hitachi tube

The remaining unused blocks of letters are assigned by mutual agreement to each assigning agency when required.

The fourth symbol designates the family member and consists of a two-digit number from 00 to 99 (later extended to three digits). It is assigned independently of the third symbol.

The fifth symbol defines the phosphor type. Color picture tube phosphors are designated by the letter X or the letters XX. For monochrome tubes the letters used are WW.

The sixth symbol is only assigned to tubes having integral neck components (permanently bonded yokes and adjustment rings). It defines the characteristics of these components and their adjustments. It consists of a two-digit number from 01 to 99 (later extended to three digits).

Note: Toshiba labels clearly show the correlation between sixth symbol and yoke. When the sixth symbol is present, a note informs that the yoke is permanently bonded to the picture tube:

When the sixth symbol is not present the note is not present either:

Manufacturers sometimes add prefix or suffix letters to type designations on their tube labels or in their commercial literature. Prefixes or suffixes are not part of the designation. The agencies assume no responsibility for the use or meaning of such additions.

Even after the introduction of the new system, manufacturers were free to use the older designation systems when necessary:

1986-made Videocolor tube with WTDS type number

1991-made Videocolor tube with Pro Electron type number

1986-made Toshiba tube with WTDS type number

1990-made Toshiba tube with EIAJ type number

The Worldwide Type Designation System (WTDS) has remained in use until the end of the CRT production era (late 2000s).

Chinese System

According to this system, the type number consists of three to four symbols.

Examples: 14SX5Y4, 37SX108Y22-DC02, 54SX503Y22, 73SX707Y22-DC26

The first symbol is a two-digit number designating the minimum diagonal in centimeters of the CRT face (e.g. 37 = 37cm).

The second symbol consists of the letters SX followed by one to three numbers designating a specific CRT family whose members have common optical, electrical and mechanical characteristics.

The third symbol consists of the letter Y followed by a number designating the phosphor type. For instance, Y22 designates a color picture tube phosphor and is the equivalent of P22 in the EIA system, B22 in the EIAJ system and X in the Pro Electron system. Y4 designates a monochrome tube phosphor and is the equivalent of P4 in the EIA system, B4 in the EIAJ system and W in the Pro Electron system.

The fourth symbol or suffix (e.g DC01, DC02, DC03, etc.), separated from the main type number by a hyphen, is only used for tubes having integral neck components (bonded yokes and adjustment rings).

Type numbers that do not belong to any of the above designation systems

Samsung proprietary system. On a few Samsung tubes the type number is very similar to a WTDS number but with notable differences. The first symbol (application category, e.g. A) is missing and the second symbol designates the diagonal measure in centimeters of the CRT face instead of the viewable screen. Also, the sixth symbol is replaced by what looks like an EIAJ suffix.

Examples: 37GDA85X-TC01, 42AGA98X-TC, 51GGB95X-TC

Other:

Tesla Ecimex (Czech manufacturer)

Examples: 561QQ22, 671QQ22

The first symbol is a two-digit number designating the minimum diagonal in centimeters of the CRT face (e.g. 67 = 67cm).

The last symbol (22 or possibly QQ22) designates a color picture tube phosphor.

Size Chart (Color Picture Tubes)

As is known, the sizing method used by consumer TV manufacturers in the US differs from that of their European and Japanese counterparts[3] in that the former use the diagonal measure (in inches) of the viewable screen while the latter use the diagonal measure (in inches) of the tube face[4]. As a result, what is called a 19-inch TV in the US is a 20-inch TV in Europe and Japan, etc. This standard industry practice simply reflects the different sizing methods of the respective tube designation systems. The introduction of a universally accepted system (WTDS) which only considers the viewable screen diagonal did not change this deep-rooted habit: European and Japanese TVs and monitors kept being marketed according to the measure of the tube face diagonal, which may be confusing when CRT products of one region are imported into another region.

The chart below lists each size as a face / screen measure in both inches and centimeters. Inch sizes are obtained by rounding up or down the actual diagonal size in centimeters. For instance, 20" (51cm) / 19V (48cm) means that a tube having a face diagonal of 51cm and a viewable screen diagonal of 48cm may be marketed as either a 20" or a 19V (i.e. 19" viewable) tube, depending on region. The third and fourth columns show the discrepancies between the actual size and the nominal market size. The fifth column indicates the screen contour design (Full Square means square corners and straight sides[5]).

TVs with this size CRTs are very uncommon. In Europe they are limited to a few Philips (e.g. 18C636), Grundig (e.g. Super Color 1820, Super Color P47-142) and Sony (e.g. Sony KV-1820E) models from the 1970s - mid 1980s.

CRT base designations

According to EIA/JEDEC the designations for base and pin connections consist of three symbols, with a hyphen between the second and the third symbol.

The first symbol is the letter B if the base includes an auxiliary (plastic) fixture for protection, insulation, identification and indexing.

The second symbol is the number of pins present in the base.

The third symbol (following a hyphen) is a three-digit number assigned in numerical sequence independent of the first two symbols. This symbol defines the unique mechanical characteristics of the base but not the materials or the electrical connections.

References

↑Until the second half of the 1980s, the trend among European TV manufacturers was to design the cabinets so that the tube face was completely visible in order to be consistent with the declared size of their models.